Quite simple really.
- French braid a preferred side of your hair
- tie an elastic band at the very end of it
- wrap your hair in a normal pony tail
- wrap a section of your pony tail around the elastic band – secure it with bobby pins
- remove the elastic band from the braid and take the braid apart
- the braid will stay where you made the whole pony tail secure
- *if you want* you can keep the entire braid in tact and have a single braid on its own in the middle of your pony tail